Cave explorers of all ages and abilities can have a field day in Arizona. Kartchner Caverns State Park®, near Benson, has been described as an underground nature preserve. Providing spectacular sights in a football-field-sized room, this living cave also features a 58-foot-tall stone column dubbed "Kubla Khan." Reservations are recommended (520-586-2283, www.azstateparks.com). Colossal Cave Mountain Park, 17 miles east of Tucson on Old Spanish Trail (520-647-7275), is a cave that has earned its name—it's one of the largest "dry," or dormant, caves in the country. In the 1880s, outlaws sought refuge in the passageways and secret exits, and rumor has it there is hidden treasure within.